Energy is consumed in heating the air infiltrating into houses maintained at temperatures above ambient. By using climatic data tapes and a daily profile f or indoor temperature of a house, it is possible to calculate factors which, in conjunction with a relationship between air change rate r and wind speed V of the form r= a +βV, enable the energy consumption due to infiltration to be calculated on a monthly basis. This has been done for Melbourne, Australia. The factors are tabulated on a monthly, annual, and heating season (April-November) basis. The energy consumption for the heating season has been plotted for a range of values of a and β along with the energy savings possible if infiltration is restricted to 0.5 air change per hour. The benefits of ‘house tightening’ are discussed.